Carry Foward under certain circumstances? Or some other solution?

I have a survey set up so that when the user inputs a "0" in a Form Field, it triggers certain follow-up questions to be hidden. If they input a number higher than zero, it requires them to complete the follow-up questions. What I dislike about this solution is that on the dashboard side of things, for the follow-up questions that were hidden, it shows "N/A", and I would prefer that have a "0" instead. Is there a way to carry foward only the "0" responses so that I don't have "N/A"? I don't want to set a default answer on these questions because I'm worried that the user will pass them over. Please advise!